When does spring officially start? Differences between meteorological and astronomical calendars explained
With March just around the corner, the arrival of spring - the season loved by many - is on the horizon. But when does spring officially begin?
According to the Met Office, the meteorological calendar divides the year into four seasons based on temperature patterns and the Gregorian calendar. This method is widely used in weather forecasting and climate studies, making it easier to compare seasonal statistics year over year.
- Spring (March 1 – May 31)
- Summer (June 1 – August 31)
- Autumn (September 1 – November 30)
- Winter (December 1 – February 28/29)
By this definition, spring always begins on March 1 and ends on May 31, ensuring consistent seasonal divisions that align with climate patterns rather than celestial events.
In contrast, astronomical spring is determined by the position of Earth in relation to the Sun, according to Royal Museums Greenwich. It begins on the vernal equinox, when day and night are nearly equal in length. The exact date varies slightly each year, but in Europe and the Northern Hemisphere, it typically falls on March 20 or 21.
The astronomical seasons are defined by:
- Spring: Begins at the Vernal Equinox (around March 20)
- Summer: Begins at the Summer Solstice (around June 21)
- Autumn: Begins at the Autumn Equinox (around September 23)
- Winter: Begins at the Winter Solstice (around December 22)
While meteorologists and climate scientists use March 1 as the official start of spring for consistency in weather data, many people recognise March 20 or 21 as the true beginning of spring due to its connection with daylight changes and the Sun’s position but ultimately, both are valid.